What it is
Rear additions and bump-outs
Chicago lots are long and narrow, so the extra room is usually behind the house. A rear addition leaves the front, and the block's look, alone.
The rear-yard setback and the lot's coverage limit how far back we can go, and the back wall of a brick house is usually load-bearing. We check both before we draw.
What's included
Footings and a foundation to match the house
Framing and a roof tied into the existing one
A beam where the old back wall opens
Windows, doors and the opening between old and new
Wiring, plumbing and heat extended
Permit drawings and the city's inspections
What changes the cost
Five things that move a rear-addition estimate
We don't print an average, because the house decides. These are the things that move your written estimate.
Footprint and the rear-yard limit
How far back the zoning lets us go, and how much yard you keep.
Foundation depth and soil
Footings go below the frost line; what the soil is like decides how.
Opening the back wall
A wide opening means a beam, and sometimes posts, to carry the load.
A kitchen or bath inside
Plumbing and cabinets cost more per square foot than a bedroom.
Matching brick or siding
New brick that suits an old wall takes sourcing and a mason.
Access and the alley
Where the dumpster and deliveries can go changes the crew's days.
How it goes
A rear addition, week by week
- Weeks 1–2
Step 1: Site visit and lot measurements, with your plat of survey
- Weeks 3–6
Step 2: Drawings, a zoning check and the engineer's footing and beam pages
- Weeks 7–14
Step 3: City plan review, as a range
- Weeks 15–16
Step 4: Permit, materials and your written schedule
- Weeks 17–28
Step 5: Build: footings, framing, roof, wiring and plumbing, finishes and inspections
Typical ranges, for planning. Your written schedule sets your weeks.
Questions about this job
How far back can we build?
The rear-yard setback and the lot's coverage set the limit. They vary by lot and zoning district, so we check yours in weeks 3 to 6 and tell you before you spend more on drawings.
Do I need a plat of survey?
Usually. It shows the lot lines and what's on them. If you can't find yours, we help you order one.
What happens when you open the back wall?
We shore the wall, set the beam and tell you the day before. The kitchen or room behind it is closed off with plastic until the new space is tied in.
What happens to the yard?
The crew stays inside a marked area and we tell you before anything near a tree or a fence moves.
Want to know if your house can do this?
Book a site visit. You get a written answer, including when it's no.